This invention relates to apparatus for measuring the rate of flow of a fluid through a conduit and, more particularly, to such apparatus which does not include any moving parts within the conduit.
There are many applications where it is desired to control the flow of a fluid through a conduit in order to fill a container with a desired amount of the fluid. For example, in an appliance such as a clothes washing machine, the user may select a desired water level depending upon the size of the load being washed. With the advent of microcomputer control of such appliances, many of the control functions previously handled by electromechanical devices have been taken over by the microcomputer. It would be desirable for the microcomputer to control the water level in such an appliance. It is therefore an object of the present invention to provide apparatus through which a microcomputer based system can control fluid levels.
Fluid level can be directly measured in a number of ways such as, for example, by providing a plurality of level sensors at different levels of the fluid container. However, it would be desirable to be able to take advantage of the computing power of the microcomputer. Fluid level may also be measured by knowing the rate at which fluid enters the container and then integrating this rate with respect to time. Thus, only a single sensor coupled between a conduit feeding the container and the microcomputer would be required. It is therefore a further object of this invention to provide a fluid flow rate sensor.
A microcomputer is digital in nature. If a sensor which is to provide an input to a microcomputer were to provide an analog output, then an analog to digital converter would be required, adding to the expense of the system. It is therefore still a further object of this invention to provide a fluid flow rate sensor which has a digital output.
Flow rate sensors are known which have moving parts, such as impellers or turbines, in the fluid flow path. Such moving parts result in a number of disadvantages, such as interfering with, and having an effect upon, the fluid flow. It is therefore another object of this invention to provide a digital fluid flow rate sensor having no moving parts in contact with the fluid flow media.